Crystallizer



y 1,1930. w. G. HALL 1,769,779

GRYSTALLIZER Filed July 51, 1929 v tionof the crystallizer.

" r G. HALL, 01E MANILA, 'PHILIPPI NE ISLANDS, ASSIGNOR OF ONE-HALF TO Y C. PITCAIRN, OF HONOLULU, TERRITORY OF HAWAII GRYSTALLIZER Application am m 31,

The invention relates to crystallizers for sugar juices and has for its object to provide a novel form of apparatus, including a tank with a helical stirrer mounted on a horizontal axis therein so as to be completely submerged in the liquor, a second helical stirrer mounted above the first so as to be-only partially submerged in the liquor and to continuously lift portions of the liquor from the body of the latter and'drop the same through the air back into the tank to efiect a uniform cooling of the liquor and thereby expedite the formation of the sugar crystals.

The invention is illustrated in the accompanying drawings, in which Fig. 1 is a longitudinal sectional eleva- Fig. 2 is a fragmentary perspective view of a modified form of the upper stirrer and elevator.

In the process of making sugar from cane or beet juice, it is necessary to concentrate the liquor to such an extent that crystallization takes'place. The crystals of sugar formed are separated from the molasses or mother liquor in centrifugals. The molasses from the, first sugar, which is made from syrup, contains a comparatively high percentage of sugar and this molasses is boiled a ain and makes a lower grade of sugar. In andling the massecuite made from molasses, it has been found advantageous to retain the massecuite, after it has beenboiled in the vacuum pans, in tanks or crystallizers. These crystallizers are usually provided with a stirring device, which keeps up. a slow circulation 0a the massecuite,therehy promoting the growth and developmentof the small grains or crystale of sugar which were formed in the vacuum pan. operation is hown in the art as crystallization in motion and the mas ,secuite is usually retained in the crystallizers for ap rox'imately six days before it is put throng centrifugals, where the crystals are separated from the molasses. It has been i found that cooling the massecuite uniformly and rapidly promotes crystallization, so that, when proper cooling is efiected, the time necessary to retain the inassecuite inthe crystallizers is greatly reduced and the resultant 1929. Serial No. 382,309.

massecuite and permitting the stirring ap-- paratus to operate approximately half in and half out of the liquor, crystallization takes place much more rapidly than when the crys-v tallizer is filled to capacity and the stirring apparatus is completely submer ed in the liquor. While this results in expe iting crystallization, the advantage is somewhat ofiset by the reduction in the output of a given crystallizer which is operated at onlyabout half capacity. The present invention is designed to provide a crystallizer of the stirrer type that will maintain the proper circulation of the liquor in the tank and will also include the advantageous operation of the ipartially submerged stirrer, which picks up t e liquor from the tank, carries the same through the air above. or in the upper part of the tank and drops it back in the form of thin sheets or streams into the tank, thereby effecting the rapid and uniform cooling necessary to expedite the formation of the sugar crystals.

A relatively simple form of ap aratus involving the invention is shown in ig. 1 of the drawings, in which 1 represents the tank of the crystallizer, which is provided with an lower part of the tank is a horizontal shaft 4 carrying a helical stirrer 8, preferably in the form of a sheet metal strip attached to vthe shaft at intervals by means of radial arms 6 and clamping collars 7 I Mounted in similar journal bearings 53 located near the top of the tankis a second shaft 10 which carries a second stirrer and liquor elevator, which, as shown, is made of a strip of T-iron or two sections of L-iron connected together to provide relatively extensive surface areas, which, in passing through the liquor, will pick up and carry portions of the liquor into the air above and drop the same in thin streams or sheets back into the tank The two helical stirrers are so disposed that the successive curved portions thereof inter-mesh as the stirrers rotatc and uniform rotary motion is imparted to each by suitable gearing, exemplified in the present case by intermeshing gears 14 and 15 of the same size, the gear 14: being driven by a Worm 16.

In operating the crystallizcr, the tank is filled to capacity, so that the lower helical stirrer operates in completely submerged relation, While the upper stirrer is only partly sulm'ierged, so that, the helical blade rotates, it operates to pick up portions of the liquor, pass the some through the air and drop it in the form oi thin sheets or streams back into the tank, with the result that the liquor is rapidly and uniformly cooled and I the crystallization oi? the sugar therein coin-- mensuratcly expedited.

Instead of: forming the helical portion oi the upper stirrer of a i" cross section, as shown in Fig. 1., the helical member may be formed of a series of spaced parallel blades or strips 13 with their edges normal to the axis of rotation, which Will largely increase the lifting and carrying capacity of: the stirrer blade and insure the liquor being dropped from the stirrer, as the latter passes through the air in the form of thin sheets or strean'is, which will still further accelerate the uniform cooling of the liquor.

What I claim is:

1. A crystallizcr eon'iprising a tank to receive the liquor to be operated. upon, a stirrer mounted in the tank and operating under conditions of com lete submersion in the liquor, and a seeon stirrer similarly mounted only partially submerged and operating to pick up portions of the liquor and drop the some through the air back into the tank.

2. A crystallizer comprising a tank to receive the liquor to be operated upon, a stirrer mounted in the tank and operating under conditions of complete submersion in the liquor and a second stirrer similarly mounted only partially submerged and operating to pick up portions of the liquor and drop the some in thin sheets through the air back into the tank,

3. A crystallizer comprising a tank to receive the liquor to be operated upon, a helical stirrer mounted on a horizontal axis and submerged in the liquor, and a second helical stirrer similarly mounted and operating partially in the liquor and partially whereby portions of the liquor are icked u by the second stirrer and droppe throng the air back into the tank.

4. A c stallizer comprising a tank to re-- ceive the iquor to be operated upon and two intermeshing helical stirrers mounted on horizontal axes in said tank, one stirrer operating in com lete submersion and the other in lpartial su mersion in the liquor in the m in the our;

5. A erystallizer comprising a tank to receive the liquor to be operated upon, horizontal shafts journaled in the upper and lower portions of said tank, a helical stirrer blade carried by the lower shaft in complete submersion, and a helical stirrer and liquor li l'ter carried by the upper shaft and operating partly in and partly out of the liquor.

6. A crystallize! comprising a tank to re ceive the liquor to be operated upon, horizontal shafts journaled in. the upper and lower portions of said tank, a helical. stirrer blade carried by the lower shaft in complete submersion, and a helical stirrer and liquor lifter including a series of spaced parallel blades with their edges normal to "the axis oi rotation carried by the upper shaft and operating partly in and. partly out of the liquor.

in testimony whereof l :llllfii my si -nature. Wliilil! /i.

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